Molecular characterisation and expression of an Arabidopsis thaliana L. MAP kinase kinase cDNA, AtMAP2K alpha

During our study of the mitogen-activated protein (MAP) kinase module in hi gher plants, we have isolated and characterised an Arabidopsis thaliana cDN A: AtMAP2K alpha, a novel member of the MAP kinase kinase family. The cDNA was obtained by screening a library from A. thaliana plantlets using the A. thaliana EST clone 127H15T7 as a probe. The deduced protein contains 348 r esidues with a calculated molecular mass of 38.3 kDa. A relationship analys is using MAP2K catalytic domain sequences from mammals, insect, fungi, yeas ts, nematode, protists and plants showed that the plant gene family identif ied to date encodes a distinct group of proteins. The results also indicate that AtMAP2K alpha is a member of a subgroup of MAP kinase kinases in plan ts. Signature sequences were identified that characterise either all MAP2Ks or only plant MAP2Ks. A Northern blot analysis revealed that the AtMAP2K a lpha transcripts were mostly detected in vegetative tissues from A. thalian a and Brassica napus plants. In both species, high transcript levels were f ound in leaves and seedlings, while much lower levels of expression were de tected in inflorescences and roots from A. thaliana and immature siliques f rom B. napus. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.